The invention relates to a method for determining quantities which characterize driving behavior using a computing device which is provided with signals indicative of steering angle, longitudinal speed of the vehicle, and two transverse accelerations, located one behind the other in the longitudinal direction of the vehicle.
A method which uses the Sagnac effect to determine yaw-angle velocity is known. In this method, monochromatic coherent light is split and guided in opposite directions on a circular path by means of light-guide cables. As a result of a rotation (yawing movement) of the light-guide cables, a rotating reference system is obtained for the split light. Since electromagnetic waves behave differently in a rotating reference system than in a stationary reference system (in conformity with the relativistic transformation equations), the interference phenomena of the split light also changes in dependence on the rotational acceleration (yaw-angle acceleration) and rotational speed (yaw-angle velocity). By evaluating these interference phenomena, the corresponding quantities of rotational movement can be determined.
A disadvantage of this method is that a light source with light capable of providing measurable interference must be provided. Moreover, the arrangement requires that the light-guide cables be mounted in such a way so as to minimize vibrations, which adversely affect interference measurements.
A linear single-track model of a vehicle is known, wherein the height of the center of gravity of the vehicle is unimportant. Thus, the center of gravity of the vehicle is shifted into the plane of the tread contact points of the wheels. Since rolling and pitching movements are thus minimized, the wheels can be modeled as one wheel in the middle of the axle. This model is described by way of example in the German Book: Zomotor, Adam: Fahrwerktechnik, Fahrverhalten, (Chassis technology, driving behavior), publisher Jornsen Reimpell, Wurzburg: Vogel 1987, ISBN 3-8023-0774-7 on pages 99 to 116. This reference does not disclose how the yaw-angle velocity and the yaw-angle acceleration can be derived from measurable quantities.
A method for determining the sideslip angle by using the yaw-angle velocity as a measurement quantity is known from German Patent specification 3,608,420. There, a sideslip angle of the vehicle is calculated by using a vehicle model and from the measurement quantities of the longitudinal speed of the vehicle, the steering-wheel angle, two transverse accelerations of the vehicle which are located one behind the other in the longitudinal direction of the vehicle, and the yaw-angle of velocity.
An object of the present invention is to design a method for determining quantities which characterize driving behavior such that as high a measuring accuracy as possible is achieved, along with as low a cost as possible.
This and other objects are, according to certain embodiments of the invention, achieved by using a computing device which is fed signals representing measured quantities of the steering angle, the longitudinal speed of a vehicle that has tires, and two transverse accelerations located one behind the other in the longitudinal direction of the vehicle, deriving further quantities using vehicle-specific quantities and a vehicle model, determining yaw-angle velocity using measured and derived quantities along with the vehicle model, wherein the vehicle model takes into account the transverse force buildup at the tires of the vehicle. The yaw-angle velocity is outputted to a vehicle control device which influences the driving behavior of the vehicle as a function of the yaw-angle velocity.
In certain preferred embodiments of the present invention, the yaw-angle velocity is independent of the driving state. In other preferred embodiments of the present invention, the sideslip angle is determined and output. Rolling movements of the vehicle can be factored into the determination of quantities and the transverse acceleration can be measured by means of transverse acceleration sensors having respective installation heights which are identical and correspond to a height of a center of gravity. The calculated quantities can be adapted according to vehicle type and the method of adaptation can employ a sliding average.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.